With respect to a press brake, a work has been hitherto bent by inserting it in the space between a punch and a die until it collides with back-gauges and then lowering the punch toward the die while the position where the work has been inserted in that way is restricted by the back-gauges.
Since a location where the work is to be bent by the press brake in cooperation of the punch with the die differs from step to step, there is a need of displacing the back-gauges at each step corresponding to the location where the work is to be bent. In addition, for the purpose of assuring operational safety during displacement of the back-gauges, there is a need of controllably displacing the back-gauges so as not to allow the back-gauges to interfere with a die assembly comprising a punch and die at all times. Indeed due to the fact that a die to be mounted on the press brake differs corresponding to the kind of work to be worked, and moreover, a region where the back-gauges interfere with die assembly differs corresponding to the kind of work to be worked, there is a need of controllably displacing the back-gauges corresponding to the kind of work to be worked.
Here, conventional typical techniques for avoiding undesirable interference of the back-gauges with the die assembly can be noted below.
1) An operator inputs into a controller (not shown) data indicative of the configuration of a die f, i.e., a lower die half of the die assembly by actuating a key board with his hands at every time when the die assembly is replaced with another one corresponding to the kind of work to be worked. As shown in FIG. 8, the foregoing data is essentially composed of a distance e from the center of the die f to an end surface of the same, a height h of the die f, a distance e from the center of a holder g for immovably holding the die f on a table (not shown) to an end surface of the same and a height h' of the holder g. On completion of the inputting operation, the controller calculates an interference region j as represented by hatched lines in the drawing based on the inputted data and then determines whether or not a target position at the foremost end of a back-gauge i enters the interference region i. Thereafter, the operator outputs results derived from the foregoing determination to the controller. PA1 2) An operator likewise calculates the interference region j based on shape data on the die f with the aid of the controller at every time when the die f is replaced with another one. Thereafter, the operator inputs into the controller data indicative of the interference region j and then controllably displaces the back-gauge j so as not allow the foremost end of the back-gauge i to enter the interference region j.
According to the conventional techniques as mentioned above, however, since there is a need of inputting data into the controller at every time when the die f is replaced with another one, operations to be performed by an operator become complicated, and moreover, a burden to be borne by the operator is enlarged unavoidably.
Indeed, since a die replacing operation is an operation to be individually performed by the operator, there arises an occasion that a die is erroneously selected by the operator when the die replacing operation is performed. Similarly, since a data inputting operation is also an operation to be individually performed by the operator, it is anticipated that data on a die different from the die for which a die replacing operation has been practically performed are erroneously inputted into the controller. In addition, there is a possibility that a die is mounted at the position offset from its preset position toward the back-gauge side.
For this reason, there arises an occasion that an interference region is settled corresponding to a die different from the die practically mounted on the press brake. Otherwise, although the die practically mounted on the press brake is correct, there arises an occasion that the settled interference region does not correspond to the position where the die has been practically mounted on the press brake. In view of the foregoing circumstance, even when the back-gauges are controllably displaced so as not allow them to enter the interference region, there is still a possibility that a malfunction of interference of the back-gauges with the die is caused.
The present invention has been made in consideration of the aforementioned background and its object resides in providing an apparatus for determining correct mounting of a die assembly on a press brake wherein an occurrence of interference of back-gauges with the die assembly due to incorrect mounting of the die assembly on the press brake can reliably be prevented without any necessity for inputting shape data into a controller at every time when the die assembly comprising a die and a punch is replaced with another one, by determining whether or not the die assembly practically mounted on the press brake coincides with a correct die assembly corresponding to the kind of work to be worked.